This invention relates to a method of winding an armature body provided with armature slots. The armature has a commutator mounted on an armature shaft and the commutator segments are provided with attachment elements. Winding wire is fed through the armature slots in accordance with a winding cycle and are attached to the attachment elements of the commutator segments to form a set of coils. The coils are electrically connected to one another via the commutator segments.
The invention also relates to an electric machine provided with a stator and an armature.
The method as described above is generally known and can be carried out with winding machines which are commercially available. Such a winding machine is described, for example, in U.S. Pat. No. 3,473,738 (herewith incorporated by reference). The known method is used to provide a drum-type armature body provided with radial armature slots with a winding distributed over a number of coils, starting from a winding wire which is wound around a hook-type attachment element of a commutator. For the purpose of forming a first coil, the winding wire is then fed a required number of times through two approximately diametrically situated armature slots and finally is wound around a further hook-type attachment element of the commutator. The winding wire is then again fed through two armature slots and wound round yet another hook-type attachment element to form a second coil. This last operation is repeated sufficiently often for the number of required spools to be formed, after which two of the spools are connected to each other via each commutator segment of the commutator by connecting the coil ends electrically to the commutator segments by bending over and heating the hook-type attachment elements. The winding time of the known method can be shortened by using two winding wires, as a result of which symmetrical winding is possible, two coils being formed at the same time.
The known method is suitable for use with thin winding wire, for example, copper wire having a diameter of less than 0.50 mm. For various applications, for example, certain electric motors which are designed for an AC voltage of 100 to 120 V, it is necessary, for considerations of temperature, to use a thicker winding wire, for example, copper wire having a diameter of greater than 0.60 mm. It has been found, however, that the percentage of rejects increases if thicker wire is used, inter alia because, after winding, coil ends touch each other at the attachment elements of the commutator or because an attachment hook is mechanically deformed during the breaking of the wire, which is brought about at the end of winding by a pulling movement.